There is no way you can stop today's total solar eclipse from happening. It is celestial, and we have no control over it. The only way to stop it would be to extinguish the sun or knock the moon or Earth out of orbit.
Over the past few millennia, people who knew nothing about eclipses couldn't explain the natural phenomena. Many cultures thought it was a sign from their sun god; it is even known to have ended full-flung battles.
Today, we understand how it works and how it looks. People chase eclipses like storm chasers chase weather.
But don't try to keep up with the eclipse. You can't catch it unless you're in a jet traveling beyond the speed of sound -- which NASA plans on doing.
Science geeks have been counting down to the millisecond for today's eclipse.
Eighties music lovers have been humming "Total Eclipse of the Heart" for weeks.
Scientists are making last-minute preparations for experiments they have been planning for years, even decades.
Professional photographers and amateur astronomers have bought and tested special solar filters for their cameras.
Even the surfers at surfline.com have gone along the Oregon coast and cleaned the lenses off their surf cameras so they can catch the first glimpses of the moon's shadow reaching the western shore.
Now, the day is here. And the rest of the country is joining in the excitement.
Sunrise, sunset and a starry night, all in the same sky
"The hair on the back of your neck is going to stand up, and you are going to feel different things as the eclipse reaches totality. It's been described as peaceful, spiritual, exhilarating, shocking," said Brian Carlstrom, deputy associate director of the National Park Service Natural Resource Stewardship and Science Directorate.
If you don't believe, stop, watch and listen.
On mountaintops and in open fields, in the middle of America's vast wilderness, people will stand together. They will stand on rooftops and city sidewalks. From big surf on beaches on the West Coast to wide-open sweeping beaches on the Eastern Seaboard, the moon's shadow will fall. Towns in the path of totality that normally have 200 people will multiply by the thousands.
Millions are forecast to flock to the very narrow -- 70 miles wide -- swath that hugs the country like a belt.
"This will be like Woodstock 200 times over -- but across the whole country," said Alex Young, solar scientist at NASA's Goddard Space Flight Center.
The Federal Highway Administration is calling this a "planned special event for which there has been no recent precedent in the United States."
The moon, which many of us often take for granted, will quite literally have its day in the spotlight.
In this celestial dance, the moon moves perfectly in between the Earth and the sun. During a total solar eclipse, the moon and the sun both appear to be about the same size from the ground.
According to NASA, this is a "celestial coincidence," as the sun is about 400 times wider than the moon and about 400 times farther away. From certain vantage points on Earth, the moon will completely block the sun. This is called totality.
Then, it is just basic geometry. When the Earth, moon and sun line up just right, the moon blocks the sun's entire surface, creating the total eclipse.
Even if you're not in totality, everyone in North America will experience some version of a partial eclipse. Just make sure that you don't look directly at the sun without your eclipse glasses.
If you pay close attention, you may notice that things you walk every day all of a sudden look a little bit different.
In New York, for example, stop by a tree in Central Park. Watch the shadows underneath the big oak trees and look for the small crescent shapes that the moon will leave fluttering on the ground.
No matter where you live in the United States, the environment around you is likely to change.
Some animals will go into their bedtime routines, while nocturnal animals will jump up from deepaily slumber. Streetlights will come on, and the stars will come out. It will be like you have sunrise, sunset and the night sky all at the same time.
Even if it's cloudy, stay a while. Experts say that the cooling from the eclipse can make some cumulus clouds dissipate just moments before the peak.
Do you have FOMO? Experts say 'don't miss it!'
Just like you count on the sun to rise every morning and set every night, you can rely on this happening precisely, down to the millisecond. In fact, NASA has made those calculations for us.
You have now probably realized that the science geek in your office asked for a day off on this random August Monday over a year ago. Now, you are stuck covering for them.
Look at your calendar and block out the hours from 1 to 3 p.m. EST. Cancel your meetings, or have them outdoors. Take a break or have a late lunch.
According to NASA, experiencing a total solar eclipse where you live happens about once in 375 years. So unless modern medicine advances considerably in the next few years, you might not make it to the next one.
The last time anyone in the United States witnessed a total solar eclipse was almost 40 years ago, on February 26, 1979. It's been even longer -- 99 years -- since a total solar eclipse crossed the country from the Pacific to the Atlantic. The total eclipse on June 8, 1918, passed from Washington to Florida.
It is an event made for sharing. This evening, we can all sit around the dinner table and say, "this is what it looked liked where I was."
It is one of the first eclipses since the beginning of our recent technological advances. Most everyone in the path will have a phone capable of taking a photo of their surroundings.
Could this eclipse be the biggest thing on social media ever? No one really knows. But it could be the biggest social media event since the presidential election in November.
If you have FOMO (fear of missing out) -- don't. We have your back. If you're not in the path of totality, still take in everything you can where you are. Or if you're in the path but socked in with clouds that won't dissipate, see how the world around you still is maybe a little bit different.
And no matter where you are in the world, you can immerse yourself in totality with us by watching the first ever live virtual reality broadcast that starts at 1 p.m.
The lunar shadow first crosses the West Coast at 9:05 a.m. PDT.
People in Lincoln City, Oregon, will be the first in the continental United States to see the total solar eclipse, beginning at 10:15 a.m.
A total solar eclipse can sometimes take as long as 7½ minutes. The longest eclipse duration for this event will occur near Carbondale, Illinois, and will clock in at two minutes, 43 seconds, beginning at 1:20 p.m. CDT.
Eventually, all good things must come to an end, and the lunar shadow will depart the East Coast at 4:09 p.m. EDT.
This will be the last total solar eclipse in the United States until April 8, 2024.
It's not quite as long of a wait as you might have thought, but the next one won't stretch the width of the country. Instead, it will move from Mexico to Maine and then traverse New Brunswick and Newfoundland.
For another eclipse similar to this year's, one that moves from coast to coast, you will have to wait until August 12, 2045.